Ignition device for liquid primers



IGNITION DEVICE FOR LIQUID PRIMERS Filed Oct. 19. 1965 gwuc/vvfm JOHN J.SCANLON, JR.

United States Patent 3,366,058 IGNITION DEVICE FOR LIQUID PRIMERS JohnJ. Scanlon, Jn, Willingboro, N.J., assignor to the United States ofAmerica as represented by the Secretary of the Army Filed Oct. 19, 1965,Ser. No. 498,161 3 Claims. (Cl. 102-70) ABSTRACT OF THE DISCLOSURE Anignition device consisting of a combustion chamber, secured in ahousing; a piston operative within the housing and combustion chamber toignite a liquid propellant and expel a flame through a small hole in thecombustion chamber.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment to me ofany royalty thereon.

Since the advent of caseless ammunition the need for a clean,combustible primer has been ever present. During repetitive firing thesolid particles in the conventional lead styphnate mix, such as antimonysulfide, would collect on the seal area and on the firing pin and causedeterioration thereof.

The invention consists of a device that can ignite alkyl nitrate liquidpropellants and expel a flame through a small hole.

Therefore, the object of the present invention is the provision of anignition device using a completely gaseous primer.

Another object is to provide an ignition device that does not requirethe use of a firing pin.

The above objects as well as others together with the benefits andadvantages of the invention will be apparent upon reference to thedetailed description set forth below, particularly when taken inconjunction with the drawing annexed hereto in which there is shown anignition device 10, consisting of a cylindrical housing 12 and acombustion chamber 14. The combustion chamber 14 has an open end 16extending into said housing and a closed end 13 extending outwardtherefrom. Said closed end 18 has an axial vent hole 20 therein. Apiston 22 is provided extending through both the housing 12 and thecombustion chamber 14. Said piston is of a diameter slightly smallerthan the combustion chamber diameter and has a radial projection 24, thediameter of which is slightly smaller than the housing diameter. Aspring or resilient means 26 is provided at the rear of said housing 12between said p'ojeCtion 24 and a cap 28. Said cap 28 is secured to saidhousing by screw threads 29. A catch means or sear 30 is providedpivotally attached at 32 to housing 12. The sear 30 is biased byresilient means or spring 34 to remain engaged with a notch 36 in piston22. The forward end of the piston 22 is provided with a high pressureseal consisting of metal rings 38 and 39, secured in radial grooves 40and 41. Between the groove 40 and the tip of the piston is a vaporpocket 42. Inlet ports 44 and 46 are provided in the combustion chamber14 and the housing 12, respectively. When the piston 22 is in the cockedposition, as shown in the drawing, the inlet ports 44 and 46 are locateda short distance in front of the tip thereof.

In operation, an alkyl nitrate liquid propellant such as ethyl nitrateis injected into the inlet ports 44 and 46.

The sear 30 is pulled down against the action of the spring 34 therebyreleasing the piston 22 through the action of the spring 26. The piston22 travels forward compressing the vapor of the liquid propellant in thevapor pocket 42. As the pressure in the vapor pocket 42 builds up, thetemperature increases. When a temperature of 450 F. is reached the vaporin said vapor pocket 42 ignites thereby igniting the remaining liquid inthe combustion chamber 14 and the liquid that is escaping through thevent hole 20. The liquid escaping through the vent hole 20 ignites thecaseless cartridge (not shown) or the like which is placed directly infront of said vent hole 20. The flame which is produced at the vent hole20 reaches 3000 F.

For example, the utilization of a vapor pocket of 0.062", a vent hole of0.013, a combustion chamber bore of 0.250", and a 15 lb. spring willyield a piston stroke of 2.50".

The piston stroke can be decreased by merely reducing the diameter ofthe vapor pocket.

Obviously many modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood, that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

I claim:

1. An ignition device comprising a housing, a combustion chamber havingan open end extending into said housing, and a closed end extendingoutward therefrom, said closed end having a vent means therein, saidcombustion chamber having inlet means coinciding with inlet means insaid housing, said inlet means provided for the insertion of a liquidpropellant, a piston extending through said housing and said combustionchamber, said piston defining a cylindrically shaped vapor pocket,located radially within said piston immediately rearwardly of theforward end thereof and being located before ignition immediately behindsaid inlet means so as to be able to collect the vapor therefrom duringits passage through said chamber, a first resilient means located in therear portion of said housing abutting a projection means on said pistonand a cap secured to the end of said housing, a catch means pivotallyattached at one end to said housing, the other end of said catch meansengaging a holding means in said piston thereby holding said piston in acocked position, said catch means being biased into said holding meansby a second resilient means on the side of said housing.

2. A device of the type described in claim 1, wherein said piston has aplurality of grooves in the vicinity of its forward end, said groovescontaining high pressure seals.

3. An ignition device comprising a cylindrical housing, a combustionchamber having an open end extending into said housing, and a closed endextending outward therefrom, said closed end having a vent hole therein,said combustion chamber having inlet ports coinciding with inlet portsin said housing, said inlet ports provided for the insertion of an alkylnitrate liquid propellant, a piston extending through said housing andsaid combustion chamber, said piston defining a cylindrically shapedvapor pocket, located radially within said piston immediately rearwardlyof the forward end thereof and being located before ignition immediatelybehind said inlet means so passage through said chamber, a first springmeans located housing, the other end of said sear engaging a notch in'said piston thereby holding said piston in a cocked position, said searbeing biased into said notch by a second spring means on the side ofsaid housing.

References Cited UNITED STATES PATENTS 2,740,385 4/1956 Haage. 2,759,4198/1956 Hitchens 61 a1 102- 39 a 4 2,947,221 8/1960 Grifiin et 61:

3,011,404 12/1961 --R-usse1l.' I A 3,097,602. 7/1963 Turner. 5 3,214,90911/1965 Gordon.

FOREIGN PATENTS 5,317 1/1826 Great Britain.

10 BENJAMIN A. BORCHELT, P/"imary Examine/ G. H. GL ANZ MAN AssistantExaminer v i

